(Part No. 2; Page No. 178)
We do not know whether the Messenger of Allah (peace be upon him) knew that the four Imams would come after him or not. This is because the Prophet (peace be upon him) did not know the Ghayb (the unseen), but knew only what Allah informed him. The causes behind dispute among scholars are many. One of the reasons is that not every one of them encompasses all knowledge. One of them may be acquainted with what is unknown to the other. One may also derive something from the texts through his understanding which was not derived by others in the absence of clear evidence.
Ibn Taymiyyah (may Allah be Merciful with him) has pointed out this point in his book Raf' Al-Malam. If you return to this book, you will find the issue in detail.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.